Compositions of organic material stabilized with certain esters of substituted hydroquinones and organic acids



United States Patent US. Cl. 260-4535 20 Claims ABSTRACT OF THEDISCLOSURE Unstable organic material is stabilized with certain estersof 2-lower alkyl-1,4-hydroquinone and derivatives thereof. Thisinvention is particularly useful in stabilizing polyolefins such aspolypropylene and polyethylene. A particularly preferred stabilizercompound is 3,5-di-t-butyl 4 hydroxyphenyl [3 (n octadecyl-mercapto)propionate.

THE INVENTION This application is a division of our co-pendingapplication Ser. No. 224,602 filed Sept. 17, 1962, now US. Patent No.3,294,836.

This invention relates to the stabilization of polypropylene and otherunstable organic material with derivatives of certain alkanoic acids, inparticular with stabilizers which are esters formed from certainsubstituted hydroquinones. The invention also relates to a method ofpreparing stabilized polypropylene and/or other organic material subjectto degradation.

More specifically, the invention pertains to stabilization ofpolypropylene and/ or other organic material normally subject tooxidative or other deterioration with a stabilizer of the Formula I:

wherein:

R is an alkyl group, especially of 3 to 8 carbon atoms,

preferably a secondary or a tertiary alkyl group, e.g. tbutyl,see-octyl,

R represents either hydrogen or one or more alkyl groups, which may bethe same or differente.g. of from 1 to 8 carbon atoms, preferably asecondary or tertiary alkyl adjacent to OH but in the case of a tertiaryalkyl group it is understood that bulky groups as the tertiary butylgroup are not contemplated in positions adjacent to one another in thephenyl nucleus;

R represents alkylthioalkyl and the group wherein:

A is alkylene, alkylenethioalkylene, or phenylene, n is 0 or 1, and Rand R are the same as above.

In the foregoing formula,

R may be methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl,

R may be methyl, ethyl, propyl, butyl, pentyl, hexyl, hep

tyl, octyl,

R may be alkylthioalkyl having 2 to 24 carbon atoms, e.g.methylthiomethyl, ethylthioethyl, propylthioethyl, butylthiopropyl,dodecylthioethyl, octadecylthioethyl, eicosylthiobutyl, etc.;

A may be alkylene or alkylenethioalkylene, in which the alkylene moietyor moieties may be methylene, ethylene, propylene, b-utylene, pentylene,hexylene, heptylene, octylene; the phenylene group may be unsubstitutedor substituted, e.g. with halogen, alkyl, alkoxy, hydroxyl, alkylthio,carboalkoxy, etc.

The compounds of the Formula I are novel and especially useful in thestabilizing of polypropylene either as sole stabilizer, or incombination with other stabilizers such as light stabilizers and/ orother thermal stabilizers, antioxidants, etc. Combinations of two ormore stabilizers of the Formula I are also useful in stabilizingpolypropylene.

In another aspect of the invention, a useful method of stabilizingpolypropylene comprises incorporating in said polypropylene astabilizing amount of a stabilizer of the Formula I wherein R R R and Aare defined the same as above, and in addition R also includes alkyl,preferably having more than 10 carbon atoms, such as alkyl from 11 to 24carbon atoms, e.g. undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl,hexadecyl, octadecyl, nonadecyl, eicosyl, heneicosyl, docosyl, tricosyl,tetracosyl.

It is an object of the invention to provide stable organic material,e.g. stable polyolefinic material, preferably stable polypropylene andpolyethylene. Preferably the polyolefins are of high molecular weight,e.g., above 1000 into the hundreds of thousands range. The polyethylenemay be of high density, medium density or low density class.

Polymeric materials such as the foregoing find use as thermoplasticmolding or coating agents. Moreover, because of their high dielectricstrength and their resistance to water, they are particularly useful asinsulators or dielectrics in condensers and other such equipment. It isknown that these polyolefins, e.g. polyethylene and polypropylene, areattacked by oxygen, particularly when exposed to the atmosphere and atelevated temperatures. For example, during use or manufacture thedesirable properties of the polyolefins may be impaired due to oxidativedeterioration. Such degradation causes loss in dielectric properties,discoloration, embrittlement, gelation, etc. Thermal degradation is alsochecked by the invention.

Not only homopolymeric material, but also copo-lymers and physicalmixtures thereof are stabilized according to the present invention. Forexample, high impact polystyrene containing copolymers of butadiene andstyrene are stabilized according to the invention.

The invention is also useful in stabilizing lubricating oils of varioustypes including aliphatic esters such as, e.g. dihexyl azelate,di-(Z-ethylhexyl) azelate, di-(3,5,5- trimethylhexyl)glutarate, di(3,5,5 trimethylpentyl) glutarate, di (2 ethylhexyl)pimelate, di (2ethylhexyl)adipate, diisoamyl adipate, triamyl tricarballylate,pentaerythritol tetracaproate, dipropylene glycol dipelargonate,l,S-pentanediol-di-(Z-ethylhexanoate), etc.

The present invention also relates to the stabilizing of fatty materialsincluding oils of animal and vegetable origin which tend to deteriorateon standing and exposure to atmospheric oxygen. Among the edible fatsand oils within the scope of the present invention are: linseed oil,menhaden oil, cod liver oil, castor oil, olive oil, rapeseed oil,

coconut oil, palm oil, corn oil, sesame oil, peanut oil, cotton seedoil, butter, fat, lard, beef tallow, etc. Other oils and fats whichdeteriorate on standing and exposure to oxygen in the air or oxygen atelevated temperatures are all within the scope of the present invention.

Within the scope of the invention also are saturated and unsaturatedhydrocarbons which tend to deteriorate on storage such as, e.g.gasolines, both natural and synthetic, in particular, saturated andunsaturated gasolines, etc.; jet fuel; diesel oil; mineral oil; fueloil; drying oil; waxes; resins; etc. Such hydrocarbons are protectedagainst gum formation, discoloration and other deterioration with thestabilizers of the present invention.

It is furthermore an object of the present invention t provide novelstabilizers of the Formula I which are versatile and effectivestabilizers in at least a single class of the foregoing organicmaterials which are normally subject to deterioration caused by exposureto light and/ or heat and/ or oxygen, etc.

A particularly preferred stabilizer of the invention is3,5-di-t-butyl-4-hydroxyphenyl B-(n-octadecylmercapto) propionate whichis especially useful in stabilizing polyolefinic material, e.g.polypropylene and polyethylene.

It is understood that the stabilizers of the invention are notnecessarily of equivalent potency. The specific stabilizer most usefulto a given unstable material will depend upon several factors for itsadvantages. Availability and cost of raw materials for the manufactureof the stabilizer and effective inhibitory action of the stabilizerincluding duration and degree of activity are among the factors whichcontrol the choice of a specific stabilizer for a specific substratewhich is normally subject to deterioration. Toxicity, color, stabilityto light and/or heat and solubility are also important factors.

In general, stabilizers of the invention are employed in a concentrationof from about 0.001% to about 5% by weight, preferably from about 0.1%to about 1% by weight. The specific concentration used varies with thesubstrate and the stabilizer, but the following ranges ar preferred.

Concentration of about 0.001% to about 1% by weight for the stabilizerin polyethylene are useful. In polypropylene from about 0.05% to about1% by weight of stabilizer is especially useful. In mineral oils,concentrations of from about 0.005% to about 1% by weight of stabilizerare used. Gasolines are stabilized with from about 0.001% to about 0.1%by weight of stabilizer, preferably about 0.05% by weight. Fattymaterial of animal origin such as lard is stabilized with from about0.001% to about 0.1% by weight of stabilizer. Oils of vegetable originsuch as cotton seed oil are similarly stabilized with from about 0.001%to about 0.1% by weight of stabilizer.

Hydrocarbon material such as cycloolefins, e.g. cyclohexene, isadvantageously stabilized with from about 0.001% to about 1% by weightof the stabilizers of the present invention. Similar concentrations ofstabilizer are used to stabilize aldehydes such as, e.g. about 0.01% byweight in heptaldehyde. High temperature lubricants which areessentially synthetic esters of alkanoic acids, e.g. trimethylolpropanetripelargonate, diisoamyladipate, are stabilized with from about 0.5% toabout 5%, preferably about 2%, by weight of a stabilizer according tothe invention.

The compounds of this invention may be used also to stabilize organicmaterial in combination with other additive agents such as, e.g.antioxidants, pourpoint depressants, corrosion and rust inhibitors,dispersing agents, demulsifiers, antifoaming agents, carbon black,accelerators and other chemicals used in rubber compounding,plasticizers, color stabilizers, heat stabilizers, ultravioletabsorbers, dyes, pigments, metal chelating agents, etc.

A particularly useful stabilizer system comprises a stabilizer of theFormula I and di-lauryl-,8-thio-di-propionate (hereinafter referred toas DLTDP). Generally from about 0.005% to about (based on the stabilizedcomposition) by weight of DLTDP and other stabilizers, e.g. of theFormula I, are employed. Polypropylene is advantageously stabilized withabout 0.1% to 0.5% by weight of DLTDP and 0.1% to 0.5 by weight of astabilizer of the Formula I. In addition, compounds similar to Formula Iwherein R is alkyl may be used in combination with DLTDP.

In place of DLTDP, other similar diesters are usefully employed with thestabilizers of the Formula I, wherein R may also be alkyl as mentionedabove, for stabilization of organic material, e.g., polypropylene. Suchdiesters as the following are useful:

n is a small number, e.g. 1 or 2; and

R and R are each independently an alkyl group, e.g. having 8 to 24carbon atoms, such as octyl, nonyl, decyl, undecyl, dodecyl, tridecyl,tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, eicosyl,heneicosyl, tricosyl, tetracosyl.

The stabilizer compounds of the Formula I are prepared in a number ofways. Thus, for example, compounds of the Formula I are prepared byreaction of the appro priate acyl halide with the appropriatesubstituted hydroquinone. It is possible to prepare most of thecompounds of the Formula I, including additionally, those compoundswherein R is alkyl in Formula I by this method. In the latter case thesimple alkanoylchloride, e.g. acetylchloride, is used. Alternatively,the appropriate acid or acid anhydride can be used.

The esters are prepared by reaction of the appropriate precursor acid,acyl halide or anhydride, and the hydroquinone, if desired in anon-polar solvent such as benzene. The reaction may be carried out in aclosed vessel under nitrogen. Pyridine is useful as a base to remove HClwhen the acyl chloride is used.

The following examples are illustrative of the invention only, and thereis no intention to limit the scope of the invention thereto. In thefollowing examples parts are by weight, unless otherwise specified, andtemperature is in degrees centigrade. The relationship between parts byweight and parts by volume is as grams to cubic centimeters.

EXAMPLES Part I.-Intermediates Example I. {3 (noctadecylmercapto)propionate acid.Methylfl-(n-octadecylmercapto)propionate is prepared from 172 parts ofl-octadecanethiol, 54.3 parts of methyl acrylate and 1 part of 40%benzyltrimethylammonium methoxide by a procedure similar to thatdescribed by Kharasch and Fuchs, J. Org. Chem. 13, (1948). The ester ishydrolyzed without isolation by the addition at 40 of parts ofisopropanol followed by 38 parts of sodium hydroxide dissolved in 90parts of water and parts of water. The reaction mixture is refluxed for1 hour at 81 and the hot solution then poured slowly with stirring into315 parts of 3 N hydrochloric acid cooled in an ice-water bath. Theprecipitated off-white solid is filtered, Washed with water until it isfree of chloride and dried. In this way 212.5 parts of the desired,B-(n-octadecylmercapto) propionic acid are obtained, M.P. 75-78".

Analysis.-Calculated for C H O S: Neutral equivalent, 358.6. Found:Neutral equivalent, 378.

Example 2./3-(n-octadecylmercapto)propionyl chloride.fl (noctadecylmercapto)propionic acid (71.7 parts) is treated with 47.6 partsof thionyl chloride at 40 and the temperature of the reaction mixture ismaintained at 2535 With stirring for /2 hour and at 35-50 for anadditional /2 hour. The excess thionyl chloride is removed bydistillation under reduced pressure. The

residue consists of 76 parts of p-(n-octadecylmercapto) propionylchloride, M.P. 32-35".

Example 3.-;8 (3,5 di-t-buty1-4-hydroxyphenyl)propionyl chloride-8-(3,S-di-t-butyl-4-hydroxyphenyl)propionic acid (8.35 parts), preparedby aqueous methanolic potassium hydroxide hydrolysis of methylfi-(3,5-di-t-butyl-4-hydroxyphenyl)propionate is added in portions to astirred solution of 7.14 parts of thionyl chloride dissolved in 30 partsof chloroform over a period of 5-10 minutes at 35-40". The temperatureof the reaction mixture is maintained at 35-40" with stirring for anadditional 2%. hours. The excess thionyl chloride and chloroform areremoved by distillation under reduced pressure. The residue consists of9 parts of pale yellow, crystalline fl-(3,5-di-tbutyl-4-hydroxyphenyl)propionyl chloride. A portion of this material isrecrystallized from petroleum ether, and it is obtained as a whitecrystalline solid melting at 71-74.

Part II.Stabilizer compounds Example 4.-3,5-di-t-butyl-4-hydroxyphenylstearate.- 2,6-di-t-butyl-1,4-hydroquinone (5.53 parts) is dissolved in45 parts of benzene with stirring under nitrogen and 1.98 parts ofpyridine are added. This solution is warmed to 45 and 7.58 parts ofstearoyl chloride are added in portions. The reaction mixture is stirredunder nitrogen at 45 for an additional 2% hours and is then cooled toroom temperature. The precipitated pyridine hydrochloride is filteredand washed with benzene, and the benzene is stripped from the combinedfiltrate and washing in vacuo. The residue (12.0 parts) crystallizes toa pale yellow waxy solid on cooling, and after recrystallizationfrommethanol, 8.5 parts of 3,5-di-t-butyl-4-hydroxyphenyl stearate areobtained as a white crystalline powder, M.P. 35-39".

Analysis.-Calculated for G i-1 0 C, 78.63%; H, 11.55%. Found: C, 78.67%;H, 11.97%.

In a similar manner by using 2,6-di-t-octyl-1,4-hydroquinone above, then3,S-di-t-octyl-4-hydroxyphenyl stearate is obtained.

Example 5.3.5-di-t-butyl-4-hydroxyphenylfi-(n-octadecylmercapto)propionate.fi (n oct-adecylmercapto) propionylchloride (75.4 parts) dissolved in 200 parts of benzene is added inportions to 44.4 parts of 2,6-di-tbutyl-1-,4-hydroquinone and 15.8 partsof pyridine dissolved in 250 parts of benzene at 40 with stirring undernitrogen. The reaction mixture is stirred for 3 /2 hours under nitrogenat 45-5 0. When the mixture has cooled to room temperature the pyridinehydrochloride which had precipitated is filtered off, and the benzenefiltrate allowed to stand over anhydrous magnesium sulfate. Afterfiltration of the benzene solution, the benzene is removed bydistillation in vacuo and the residue, 120 parts of a brownish syrup,crystallizes. The crude product is washed and triturated with methanol,dried, and recrystallized from petroleum ether. In this way 72 parts ofwhite, crystalline 3,5-di-t-butyl-4-hydroxyphenylB-(n-octadecylmercapto) propionate are obtained, M.P. 51.5-53.

Analysis.'-Calculated for C H O S: C, 74.67%; H, 11.10%; S, 5.70%.Found: C, 74.64%; H, 10.99%; S, 5.78%.

Example 6.-Bis(3,5-di-t-butyl-4-hydroxyphenyl)adipate.-2,6-di-t-buty1-1,4-hydroquinone (8.88 parts) and 3.16 parts ofpyridine are dissolved in 45 parts of benzene with stirring undernitrogen. The solution is warmed up to 40 and 3.66 parts of adipylchloride are added in portions. The reaction mixture is stirred undernitrogen at 45 for 3 hours. An additional 8 parts of benzene are addedduring the last half hour. After the reaction mixture has cooled to roomtemperature, the insoluble solid (12.5 parts) is filtered, washed withbenzene and dried. The solid, which is a mixture of pyridinehydrochloride and the desired product, is taken up in 60 parts of waterand 70 parts of ether, shaken well and the layers separated. The etherlayer is washed once with 30 parts of water, filtered, and the etherremoved in vacuo. The

residue (7 parts) is recrystallized from a mixture of hexane and ethylacetate (3:1 by volume), and 4.5 parts of white, crystalline bis(3,5-di-t-butyl-4-hydroxyphenyl) adipate are obtained, M.P. 157-l59.

Analysis.-Calculated for C H O C, 73.61%; H, 9.09%. Found: C, 73.91%; H,8.98%.

Example 7.-Bis(3,S-di-t-butyl-4-hydroxyphenyl)sebacate.2,6-di-t-butyl-1,4-hydroquinone (8.88 parts) and 3.16 parts ofpyridine are dissolved in 45 parts of benzene with stirring undernitrogen. The solution is warmed to 44 and 4.78 parts of sebacylchloride are added in portions. The reaction mixture is stirred under anitrogen atmosphere at 45-50 for 3 hours. After the reaction mixture hascooled to room temperature, the precipitated pyridine hydrochloride isfiltered, and the benzene filtrate concentrated to dryness in vacuo. Thecrude residue (13.5 parts) is dissolved in 30-40 parts of petroleumether and the solution is washed once with 10 parts of 5% sodiumcarbonate and twice with 10 parts of water. The petroleum other solutionis warmed on the steam bath a few minutes, allowed to cool slowly, andfinally refrigerated. The crystalline product (7.5 parts) obtained uponfiltration of the cold solution is triturated with warm petroleum ether,refrigerated, filtered, washed with cold petroleum ether and dried. Inthis manner, 65 parts of white, crystallinebis(3,5-di-t-butyl-4-hydroxyphenyl) sebacate are obtained, M.P. 98100.

Analysis.-Calculated for C H O C, 74.71% H, 9.57%. Found: C, 74.87%; H,9.71%.

Example 8.-Bis(3,5-di-t-butyl-4-hydroxyphenyl) 3,3-thiodipropionate.-2,6-di-t-butyl-1,4-hydroquinone (8.88 parts) and 3.16parts of pyridine are dissolved in 45 parts of benzene with stirringunder nitrogen. The solution is warmed to 40-50 and 4.94 parts of3,3'-thiodipropionyl chloride, B.P. 126-127/ 1.5 mm., n 1.5169, areadded in portions. (The acid chloride is prepared from3,3'-thiodipropionic acid and excess thionyl chloride in 71% yield, seeSchmidt and Schnetzer, Helv. Chim. Acts 34, 894-7 (1951). The reactionmixture is maintained at 40-50 with stirring in a nitrogen atmospherefor 3 hours. After the reaction mixture has cooled to room temperature,the precipitated pyridine hydrochloride is filtered, and the benzenefiltrate is concentrated to dryness in vacuo. The crude residue (13parts) is dissolved in 70 parts of ether and the ether solution washedin turn with 50 parts of water, 30 parts of 5% sodium hydroxide andtwice with 30 parts of water. The ether solution is dried over anhydrousmagnesium sulfate, filtered, the ether removed in vacuo, and thecrystalline residue (10.5 parts) is recrystallized from hexane. In thisway, 7.5 parts of white, recrystalline bis3,5-di-t-butyl-4-hydroxyphenyl) 3,3 '-thiodipropionate are obtained,M.P. 118-120.

Analysis.Calculated for C H O S: C, 69.59%; H, 8.59%; S, 5.46%. Found:C, 69.25%; H, 8.42%; S, 5.66%.

Example 9.-Bis (3,5 di-t-butyl-4-hydroxyphenyl) terephthalate.-2,6di-t-butyl-1,4-hydroquinone (11.1 parts) and 3.95 parts of pyridine aredissolved in 40 parts of benzene with stirring under nitrogen. Thesolution is warmed to 45-47 and 5.08 parts of terephthaloyl chloridedissolved in 20-25 parts of benzene are added in portions. The reactionmixture is maintained with stirring for 3 hours at 45-50 under anitrogen atmosphere. When the reaction mixture has cooled to roomtemperature, the precipitated solid (18 parts) which consists of boththe desired product and pyridine hydrochloride, is filtered, washed withbenzene, and dried. The solid is stirred for a short period in 100 partsof water containing a drop of sodium lauryl sulfate, filtered, and thefilter cake Washed until the wash liquors are free of chloride ion. Thedried bis( 3,5 di-t-butyl-4-hydroxyphenyl) terephthalate (12 parts) isobtained as a white, crystalline powder, M.P. 269-2725".

Analysis.Calculated for C H O C, 75.23%; H, 8.07%. Found: C, 74.90%;H,7.95%.

Example 10.3 t butyl 4 hydroxyphenyl B-(noctadecylmercapto)propionate.-B (n octadecylmercapto)propionyl chloride (11.3 parts)dissolved in 35 parts of benzene is added in portions to 4.98 parts of2-t-butyl- 1,4-hydroquinone and 2.37 parts of pyridine dissolved in 40parts of benzene at 42 with stirring under nitrogen. The reactionmixture is stirred for 2 /2 hours under nitrogen at 4550. When themixture has cooled to room temperature, the pyridine hydrochloride whichhad precipitated is filtered ofi and the benzene filtrate treated with60 parts of ether and 50 parts of water. The mixture is shaken and thelayers separated. The benzeneether layer is washed twice with 30 partsof water and dried over anhydrous magnesium sulfate. After the solutionis filtered, the solvents are removed by distillation in vacuo, and thecrude crystalline residue (14.5 parts) is recrystallized from petroleumether. In this manner 11.5 parts of the desired product are obtained asan ofi-white crystalline powder, M.P. 58-60".

Analysis.Calculated for C H O S: C, 73.46%; H, 10.74%; S, 6.33%. Found:C, 73.53%; H, 10.73%; S, 6.44%.

Example 11.Bis(3 t butyl 4 hydroxyphenyl) adipate.2 t butyl 1,4hydroquinone (16.6 parts) and 7.9 parts of pyridine are dissolved in 110parts of benzene with stirring under nitrogen. The solution is warmed to45 and 9.15 parts of adipyl chloride are added in portions. An oilprecipitates almost immediately. The reaction mixture is stirred undernitrogen at 4550 for 4 /2 hours. A portion of the benzene solvent isremoved by evaporation and the concentrate is treated with 150 parts ofwater and 175 parts of ether, the mixture shaken, and the layersseparated. The ether layer is washed twice with 75 parts of water, theether solution filtered, and the ether removed in vacuo. The crude solidresidue (30 parts) is recrystallized from a mixture of hexane and ethylacetate (2:1 by volume), and 12.5 parts of the desired product areobtained as a white, crystalline powder, M.P. 168171.S.

Analysis.Calculated for C H O C, 70.56%; H, 7.74%. Found: C, 70.56%;H,7.64%.

Example 12.Bis(3 t butyl 4 hydroxyphenyl) sebacate.2 t butyl1,4-hydroquinone (16.6 parts) and 7.9 parts of pyridine are dissolved in110 parts of benzene with stirring under nitrogen. The solution iswarmed to 47 and 12 parts of sebacyl chloride are added in portions. Anoil precipitates almost immediately. The reaction mixture is stirredunder a nitrogen atmosphere at 45-50 for 3-4 hours. A portion of thebenzene solvent is removed by evaporation and the remainder of thebenzene is decanted from the now solidified oil. The solid is taken upin 150 parts of water and 175 parts of ether, the mixture shaken, andthe layers separated. The ether layer is washed in turn with 75 parts ofwater, 75 parts of water containing parts of 10% sodium carbonate andparts of saturated sodium chloride, and twice with 75 parts of water.The ether solution is dried over anhydrous magnesium sulfate, filtered,and the ether removed in vacuo. The residual viscous yellow syrup (21.5parts) is crystallized by trituration with n-hexane and purified bytrituration and washing with petroleum ether. The dried product isobtained as a white, crystalline powder (19.5 parts), M.P. 75-795".

Analysis-Calculated for C H O C, 72.26%; H, 8.49%. Found: C, 71.99%; H,8.43%.

Example 13.Bis(3 t butyl 4 hydroxyphenyl) 3,3' thiodipropionate.2 tbutyl 1,4 hydroquinone (10.2 parts) and 484 parts of pyridine aredissolved in 6570 parts of benzene with stirring under nitrogen. Thesolution is warmed to 47 and 6.6 parts of 3,3-thiodipropionyl chlorideare added in portions. The reaction mixture is maintained at 45-50 withstirring in a nitrogen atmosphere for 2 hours. After the reactionmixture has cooled to room temperature, the benzene layer is siphonedofi from the precipitated oily lower layer and the residual oil is takenup in 100 parts of water and 105 parts of ether. The mixture is shakenand the layers separated. The ether layer is washed in turn with 50parts of water, 50 parts of water containing 6 parts of 10% sodiumcarbonate, 50 parts of water containing 10 parts of saturated sodiumchloride solution, and finally, twice with 50 parts of water. The etherlayer is dried over anhydrous magnesium sulfate, filtered, and the etherthen removed in vacuo. The residue (14.5 parts), a yellow glass, istriturated and washed with hot petroleum ether and dried.

Analysis.Calculated for C H O S: C, 65.80%; H, 7.22%; S, 6.76%. Found:C, 66.19%; H, 7.35%; S, 6.62%.

Example 14.-Bis(3 t butyl 4 hydroxyphenyl) terephthalate.-2 t butyl1,4-hydroquinone (8.3 parts) and 3.95 parts of pyridine are dissolved in45 parts of benzene and 5.08 parts of terephthaloyl chloride dissolvedin 25 parts of benzene are added (see Example 9). The reaction iscarried out and the desired product, 11 parts, M.P. 259-265 (decomp.),is isolated as described in the above Example 9.

Analysis.Calculated for C H O C, 72.71%; H, 6.54%. Found: C, 72.51%; H,6.31%.

Example 15.3,5 dit butyl 4 hydroxyphenyl laurate.2,6 dit butyl 1,4hydroquinone (5.53 parts) is treated with 5.50 parts of lauroyl chloridein the presence of 1.98 parts of pyridine dissolved in 45 parts ofbenzene (see Example 4). The reaction is carried out and the crudeproduct (10 parts) is isolated as described in Example 4. Forpurification, the crude product is dissolved in 20 parts of petroleumether, the solution extracted with 10 parts of 5% sodium carbonate andthe layers separated. The petroleum ether solution is dried overanhydrous magnesium sulfate, filtered, and the petroleum ether strippedoff in vacuo. In this manner, 8.5 parts of 3,5-di-tbutyl-4-hydroxyphenyllaurate are obtained as a pale yellow viscous oil.

Analysis.-Calculated for C H O C, 77.18%; H, 10.96%. Found: C, 77.48%;H, 10.97%.

Example 16.-3,5 di tbutyl-4-hydroxyphenyl acetate.2,6 dit-butyl-1,4-hydroquinone (22.2 parts) is treated with 7.85 parts ofacetyl chloride in the presence of 7.9 parts of pyridine dissolved inparts of benzene as described in Example 4. The reaction mixture isstirred under nitrogen at 4550 for 3 hours and is then cooled to roomtemperature. The precipitated pyridine hydrochloride is filtered andwashed with benzene and the combined filtrate and washings, after dryingover magnesium sulfate, are evaporated to dryness in vacuo. The residue(23.5 parts) crystallizes to a yellow solid, and after recrystallizationfrom petroleum ether, 13 parts of 3,5-di-tbutyl-4-hydroxyphenyl acetateare obtained as white crystals, M.P. 8689.

Analysis.-Calculated for C H O C, 72.62%; H, 9.15%. Found: C, 72.43%; H,9.18%.

Example 17.3,5 di-t-butyl-4-hydroxyphenyldocosanoate.2,6-di-t-butyl-1,4-hydroquinone (5.55 parts) is treated with9 parts of docosanoyl chloride (prepared from docosanoic acid andphosphorus trichloride) dissolved in 18 parts of benzene in the presenceof 1.98 parts of pyridine dissolved in 27 parts of benzene as describedin Example 4. The reaction is carried out and the crude product (13parts) is isolated as described in Example 4, except that the benzenefiltrate from pyridine hydrochloride is dried over sodium sulfate beforethe benzene is removed. The crude crystalline product is recrystallizedtwice from methanol, plus a small amount of isopropano-l and finally istriturated with hexane at room temperature. The insoluble material isfiltered off and washed with a minimum amount of hexane, and the clearhexane filtrate is refrigerated, filtered, and the white crystals washedonce with ice-cold hexane. In this manner, 3 parts of3,5-di-t-butyl-4-hydroxyphenyl docosanoate are obtained, M.P. 59-615".

Analysis.Calculated for C H O C, 79.35%; H, 11.84%. Found: C, 79.15%; H,11.80%.

Example l8.3,5 di t-butyl-4-hydroxyphenyl ,8-(3,5- di tbutyl-4-hydroxyphenyl)propionate.2,6-di-t-butyl- 1,4-hydroquinone (6.66parts) is treated with 8.96 parts of}8-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl chloride dissolved in 14parts of benzene in the presence of 2.37 parts of pyridine dissolved in31 parts of benzene as described in Example 4. The reaction is carriedout and the crude product (13.5 parts) is isolated as described in Ex-Part III.--Stabilization of unstable material Example 19.Stabilizationof po1ypropylene.Unstabilized polypropylene powder (Hercules Profax6501) is thoroughly blended with 0.5% by weight of3,5-di-tbutyl-4-hydroxyphenyl ,B-(n-octadecylmercapto) propionate. Theblended material is then milled on a two rolle-r mill at 182 for 5minutes, after which time the stabilized polypropylene is sheeted fromthe mill and allowed to cool.

The milled polypropylene sheet is then cut into small pieces and pressedfor 7 minutes on a hydraulic press at 218 and 2000 pounds per squareinch pressure. The -resultant sheet of 25 mil thickness is then testedfor resistance to accelerated aging in a forced draft oven at 149. Theresultant composition of 0.5% by weight of 3,5-di-tbutyl 4-hydroxyphenylB-(n-octadecylmercapto)propionate and polypropylene is stabilizedagainst oxidative deterioration for more than 1000 hours. Theunstabilized polypropylene deteriorates after only 3 hours.

In like manner as in this example, stabilized compositions ofpolypropylene are prepared having 0.5% by weight of each of thefollowing:

3,S-di-t-butyl-4-hydroxyphenyl stearateBis(3,5-di-t-butyl-4-hydroxyphenyl) adipateBis(3,5-di-t-butyl-4-hydroxyphenyl) sebacateBis(3,5-di-t-butyl-4-hydroxyphenyl) 3,3'-thiodipropionateBis(3,5-di-t-butyl-4-hydroxyphenyl) terephthalate3-t-butyl-4-hydroxyphenyl fi-(n-octadecylmercapto) propionateBis(3-t-butyl-4-hydroxyphenyl) adipate Bis(3-t-butyl-4-hydroxyphenyl)sebacate Bis(3-t-butyl-4-hydroxyphenyl) 3,3-thiodipropionateBis(3-tbutyl-4 hydroxyphenyl) terephthalate3,5-di-t-butyl-4-hydroxyphenyl laurate 3,5-di-t-butyl-4-hydroxyphenylacetate 3,5-di-t-butyl-4-hydroxyphenyl docosanoate 3,5 di tbutyl-4-hydroxyphenyl B(3,5-di-t-butyl-4-hydroxyphenyl) propionate.

In a similar manner as in this example, stable compositions ofpolypropylene are prepared with 0.1% by weight of a compound accordingto each of the preceding examples in Part II, together with 0.5% byweight of dilauryl-fi-thiodipropionate. In some cases the improvement isso remarkable that a synergistic effect is observed in the oven-agingtest. For example, 0.1% of 3,5-di-t-butyl- 4 hydroxyphenyl ,8(n-octadecylmercapto)propionate stabilizes polypropylene for 53 hours,while 0.5% of dilauryl ,8 thiodipropionate stabilizes polypropylene 335hours, but a combination of these two stabilizers in the above amountsstabilizes polypropylene 665 hours or 277 hours beyond what could bepredicted on the basis of a mere additive effect.

Example 20.Stabilization of mineral oil.A waterwhite, refined (U.S.P.grade) mineral oil (Esso P-rimol D) is stabilized under the followingtest conditions.

A sample of mineral oil (10 parts) is placed in a Slightype oxidationflask filled with oxygen at room temperature (25) and atmosphericpressure. Thereafter, the flask is sealed to form a system having amercury manometer which measures the pressure changes as oxygen isabsorbed by the sample in the flask. The sample is then heated at untilthe manometer registers a decrease of 300 mm. Hg pressure Within theflask with reference to the maximum pressure obtained at 150. Thestabilized mineral oil contains 0.1% by weight of 3,5-di-t-butyl-4-hydroxyphenyl fi-(n-octadecylmercapto propionate.

Example 21.Stabilization of a resin containing elastomer.High impactpolystyrene resin containing elastomer (i.e. butadiene-styrene) isstabilized against loss of elongation properties by incorporation of0.5% by weight of 3,5 di t-butyl- 4-hydroxyphenyl,B-(n-octadecylmercapto)propionate. Under the test conditions describedhereinbelow, the stabilized resin retains a higher percentage of itsoriginal elongation properties, Whereas the unstabilized resin retainsless elongation properties.

The unstabilized resin is dissolved in chloroform and the stabilizerthen added, after which the mixture is cast on a glass plate and thesolvent evaporated to yield a uniform film which, upon drying, isremoved and cut up, and then pressed for 7 minutes at a temperature of163 and a pressure of 2000 pounds per square inch into a sheet ofuniform thickness (25 mil). The sheets are then cut into strips,approximately 4 X 0.5 inches. A portion of these strips is then measuredfor length of elongation in the Instron tensile tester (InstronEngineering Corporation, Quincy, Mass). The remaining portion of thestrips is aged in a forced draft oven for 6 weeks at 75 and thereaftertested for elongation.

Similar results are obtained with a terpolymer ofacrylonitrile-butadiene-styrene.

What is claimed is:

1. A composition of matter stabilized against deterioration whichcomprises polyolefin material normally subject to deterioration and astabilizing amount of the stabilizing compound of the formula:

wherein:

R is alkyl of 3 to 8 carbon atoms,

R is a member selected from the group consisting of hydrogen and alkylof 1 to 8 carbon atoms,

R is a member selected from the group consisting of alkylthioalkyl of 2to 24 carbon atoms, alkyl of 1 to 24 carbon atoms, and the radical ofthe formula R and R are the same as above, and

n is a member selected from the group consisting of 0 and 1, and

A is a member selected from the group consisting of lower alkylene,lower alkylenethio (lower alkylene) and phenylene.

2. A composition of matter as claimed in claim 1 wherein the polyolefinmaterial is polypropylene and the stabilizing compound is3,5-di-t-butyl-4-hydroxyphenyl p-(n-octa decylmercapto) propionate.

3. A composition of matter as claimed in claim 1 wherein the polyolefinmaterial is polypropylene and the stabilizing compound isbis(3,5-di-t-butyl-4-hydroxyphenyl) adipate.

4. A composition of matter as claim in claimed 1 wherein the polyolefinmaterial is polypropylene and the stabilizing compound is bis(3,5di-t-butyl-4-hydroxyphenyl) sebacate.

5. A composition of matter as claimed in claim 1 wherein the polyolefinmaterial is polypropylene and the stabilizing compound is bis(3,5di-t-butyl-4-hydroxyphenyl) 3,3'-thiodipropionate.

6. A composition of matter as claimed in claim 1 wherein the polyolefinmaterial is polypropylene and the stabilizing compound is his(3,5-di-t-butyl-4-hydroxyphenyl) terephthalate.

7. A composition of matter as claimed in claim 1 wherein the polyolefinmaterial is polypropylene and the stabilizing compound is3-t-butyl-4-hydroxyphenyl B-n-(octadecylmercapto) propionate.

8. A composition of matter as claimed in claim 1 wherein the polyolefinmaterial is polypropylene and the stabilizing compound isbis(3-t-butyl-4-hydroxyphenyl) adipate.

9. A composition of matter as claimed in claim 1 wherein the polyolefinmaterial is polypropylene and the stabilizing compound isbis(3-t-butyl-4-hydroxyphenyl) sebacate.

10. A composition of matter as claimed in claim 1 wherein the polyolefinmaterial is polypropylene and the stabilizing compound isbis(3-t-butyl-4-hydroxyphenyl) 3,3'-thiodipropionate.

11. A composition of matter as claimed in claim 1 wherein the polyolefinmaterial is polypropylene and the stabilizing compound isbis(3-t=butyl-4-hydroxyphenyl) terephthalate.

12. A composition of matter as claimed in claim 1 wherein the polyolefinmaterial is polypropylene and the stabilizing compound is3,5-di-tbutyl-4-hydroxyphenyl 8- 3 ,5 -di-t-butyl-4-hydroxyphenyl)propionate.

13. A composition of matter as claimed in claim 1 wherein the polyolefinmaterial is polypropylene and the stabilizing compound is3,5-di-t-butyl-4-hydroxyphenyl acetate.

14. A composition of matter as claimed in claim 1 wherein the polyolefinmaterial is polypropylene and the stabilizing compound is3,5-di-t-butyl-4-hydroxypheny1 docosanoate.

15. A composition of matter as claimed in claim 1 wherein the polyolefinmaterial is polypropylene and the stabilizing compound is3,5-di-t-butyl-4-hydroxyphenyl stearate.

16. A composition of matter as claimed in claim 1 wherein the polyolefinmaterial is polypropylene and the stabilizing compound is3,5-di-t-butyl-4-hydroxyphenyl laurate.

17. A composition of matter which comprises polyolefin material which isnormally subject to deterioration and a stabilizer system consistingessentially of a mixture of (a) a stabilizer of the formula R: wherein:

R is an alkyl group of 3 to 8 carbon atoms,

R is a member selected from the group consisting of alkyl of l to 8carbon atoms, and hydrogen,

R is a member selected from the group consisting of alkyl of 1 to 24carbon atoms, alkylthioalkyl of 2 to 24 carbon atoms, and the radical ofthe formula:

flabloilm wherein:

A is a member selected from the group consisting of lower alkylene,lower alkylenethio (lower alkylene) and phenylene,

l 2 n is a member selected from the group consisting of 0 and l, and Rand R are as described above, and (b) a stabilizer of the formula:

wherein:

n is a member selected from the group consisting of 1 and 2, and R and Rare each independently an alkyl group of 8 to 24 carbon atoms.

18. A composition of matter as defined in claim 17 wherein thepolyolefin material is polypropylene.

19. A composition of matter as defined in claim 17 wherein thepolyolefin material is polypropylene, (a) is 3,5 di tbutyl-4-hydroxyphenyl ,B-(n-octadecyl), mercapto propionate, (b) isdi-lauryl-fl-thiodipropionate.

20. A stabilizer system consisting essentially of (a) a stabilizer ofthe formula O Ho-0-ii-Ra R2 wherein:

R is an alkyl group of 3 to 8 carbon atoms,

R is a member selected from the group consisting of alkyl of 1 to 8carbon atoms, and hydrogen,

R is a member selected from the group consisting of alkyl of 1 to 24carbon atoms, alkylthioalkyl of 2 to 24 carbon atoms, and the radical ofthe formula:

' [HO-Q- 0-6 ,.A--]

wherein:

A is a member selected from the group consisting of loweralkylenethio(lower alkylene), and phenylene,

n is a member selected from the group consisting of 0 and l, and

R and R are as defined above, and

(b) a stabilizer of the formula ?H2(CH2)11COOR5 s $HZ(CH2)11C 0 OR!wherein:

n is a member selected from the group consisting of 1 and 2, and

R and R are each independently an alkyl group of 8 to 24 carbon atoms.

References Cited UNITED STATES PATENTS 3,255,136 6/1966 Hecker et al.26045.85 3,303,211 2/1967 Peterson et al. 260471 3,330,859 7/1967 Dexteret al. 260473 3,338,833 8/1967 Dexter et al. 26045.85 3,364,250 1/1968Dexter et al. 260473 3,367,908 2/1968 Dexter et al. 26045.85

DONALD E. CZAJ A, Primary Examiner V. P. HOKE, Assistant Examiner US.Cl. X.R.

